The present invention relates to a new and improved construction of a sieve or screening apparatus comprising a rotatable circular sieve or screen, equipped with a feed or conveyor worm, the helical surface of which bears against the inner wall of the circular sieve or screen.
Heretofore known sieve or screening equipment of this type possess a substantially cylindrical circular sieve, which has sieve openings or holes distributed over its entire circumferential surface. Circular sieves or screens of this type are used for concentrating suspensions of solid substances in liquids, as a rule water, but also for separating coarser substances. Thus, for instance, in the papermaking industry there are already known sieve or screening equipment of this type, which during the processing of wastepaper, serves to wash-out useful paper fibers from separated-out contaminants or rejects. The paper fibers pass through the sieve or wire which is provided with suitable openings, whereas the larger size contaminants or rejects which are to be separated, such as, for instance, foil pieces, wires, textile pieces and so forth, remain at the sieve and thereafter are eliminated. However, it is also possible, when working with correspondingly finer sieves or screens to remove through the sieve materials such as fillers, fine substances and fine contaminants or rejects, whereas the cleaned fiber substances remain at the sieve.
The efficiency of the washing operation, with the heretofore known circular or cylinder sieves is however inadequate, so that in many instances it is necessary to use dynamic jarrers or vibrators. But this type of equipment is noisy, prone to malfunction and has a poor sorting capability.